protocol status down

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Hi
Whatever I learnt in ccna till now regarding the line and protocol status made me doubt the answer of this question which goes like this-




A network technician is unable to ping from R1 to R2.What will help correct the problem?


A Ensure that the serial cable is correctly plugged in to the interfaces.

B Apply the clock rate 56000 configuration command to the serial0/l interface of R1.

C Configure the serial0/1 interfaces on R1 and R2 with the no shutdown command.

D Change the address of the serial0/1 interface of R1 to 192.1.1.4.

E Change the subnet masks of both interfaces to 255.255.255.240.

I feel the answer should be option B ,since there is no clock rate showing in the output of the "sh int serial 0/1" but since at least there should be a DCE end with clock rate applied.
The answer that is shown is option A to my disbelief!!
Can anyone throw some light why option A should be the answer and not B?

 

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Wish I could but I also think that B is the correct option. I checked to ensure it:

Output simulated with missing clock rate:

Code:

Router(config-if)#do sh int s0/0
Serial0/0 is up, line protocol is down (disabled)
  Hardware is HD64570
  Internet address is 192.168.1.2/30
  MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Now watch:

Code:

Router(config-if)#clock rate 56000
Router(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up

Router(config-if)#do sh int s0/0
Serial0/0 is up, line protocol is up (connected)
  Hardware is HD64570
  Internet address is 192.168.1.2/30
  MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, loopback not set, keepalive set (10 sec)

A is wrong because I don't think the port would be up without a link
C is plain wrong because it would say administratively down (or similar)
D is plain wrong as it moves one end out of the same subnet, and the issue is below layer 3
E is plain wrong as this is an incorrect subnet mask, and the issue is below layer 3

I open myself to being corrected as I don't use serial links much, or ever since I did CCNA, but I think you are bang on here. However, your reasoning is wrong, clock rate is not shown in show interface.

 

Thanks bro for confirmation